How many images will you see when two plane mirrors are perpendicular to each other?

The correct option is A

3

For two mirrors placed at any angle, the number of images formed by the mirrors can be determined by:
$N=\left(\frac{{360}^{\circ }}{\theta }\right)-1$
$N=\left(\frac{{360}^{\circ }}{\theta }\right)-1$ is the angle between the mirrors and N is the number of images formed. For parallel mirrors
$\theta =0$, hence $N=\infty$, so the answer is 3.